Listen before talk for cellular in unlicensed band

ABSTRACT

Disclosed in some examples are systems, machine-readable media, methods, and cellular wireless devices which implement a Listen Before Talk (LBT) access scheme for a device operating according to a cellular wireless protocol in an unlicensed channel. A cellular wireless device may utilize the cellular wireless protocol in the unlicensed channel after the LBT access scheme has determined that a channel (a defined range of frequencies) in the unlicensed channel is idle for a particular period of time.

PRIORITY CLAIM

This patent application claims the benefit of priority under 35 U.S.C.Section 119 to U.S. Provisional Patent Application Ser. No. 62/019,316,filed on Jun. 30, 2014, which is hereby incorporated by reference hereinin its entirety.

TECHNICAL FIELD

Embodiments pertain to cellular wireless technologies. Some embodimentsrelate to cellular wireless technologies operating in unlicensedcommunication bands.

BACKGROUND

Cellular technologies typically operate in a licensed frequencyspectrum. A licensed frequency spectrum is a range of frequencies thatare exclusively assigned to a particular entity (e.g., a particularwireless carrier) for use. As the available licensed frequency spectrumsare limited and as demand rises for cellular wireless services, theamount of free assigned spectrum available for use is limited.

In contrast to licensed frequency spectrums, there are variousunlicensed frequency spectrums which allow for use of certainfrequencies without an entity obtaining legal approval. Thesefrequencies are shared amongst devices which wish to use them, anddevices that use these spectrums have protocols to allow them to sharethe spectrum with other devices. Often these unlicensed spectrums arenot licensed primarily for cellular wireless uses, and often thesespectrums are subject to contention or utilization by other devices.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which are not necessarily drawn to scale, like numeralsmay describe similar components in different views. Like numerals havingdifferent letter suffixes may represent different instances of similarcomponents. The drawings illustrate generally, by way of example, butnot by way of limitation, various embodiments discussed in the presentdocument.

FIG. 1A is a timeline of a Listen Before Talk (LBT) method according tosome examples of the present disclosure.

FIG. 1B is a flowchart of a LBT method according to some examples of thepresent disclosure.

FIG. 2A is a timeline of a LBT method according to some examples of thepresent disclosure.

FIG. 2B is a flowchart of a LBT method according to some examples of thepresent disclosure.

FIG. 3 is a flowchart of a LBT method with a backoff according to someexamples of the present disclosure.

FIG. 4 is a schematic of a cellular wireless device according to someexamples of the present disclosure.

FIG. 5 is a block diagram illustrating an example of a machine uponwhich one or more embodiments may be implemented.

DETAILED DESCRIPTION

As demand for licensed spectrum for cellular wireless protocols such asLong Term Evolution (LTE) increases, designers of LTE systems have begunto explore the use of these licensed protocols in unlicensedfrequencies. Usage of cellular and other licensed protocols inunlicensed frequencies presents certain challenges.

For example, cellular wireless devices (e.g., a base station or a mobiledevice such as a smart phone) utilize licensed channels which ensurethat these devices have exclusive use of the particular wirelesschannel. A “channel” is a band of (usually but not always contiguous)frequencies used for wireless communications. As a result, a designassumption of these cellular protocols is that they have exclusiveaccess to the frequencies on which they operate. They are generally onlyconcerned with coordinating amongst other devices participating in thesame network. For example, in LTE systems, a base station (an eNodeB)typically coordinates transmission and reception from one or more UserEquipment (UE) that are associated with the eNodeB. The eNodeB generallydoes not consider other users in other networks when planningtransmission and reception of data. If a cellular wireless network begantransmitting in the unlicensed channel without modification, thecellular wireless devices would transmit and receive continuously. Thiswould prevent other devices from utilizing the channel.

In contrast, devices operating in unlicensed channels consider not onlydevices operating in a single network (e.g. controlled by a singleoperator), but devices operating in many different networks and devicesoperating using other protocols. For example, devices operatingaccording to wireless protocols such as an 802.11 standard defined bythe Institute for Electrical and Electronics Engineers (IEEE) (Wi-Fi)consider not only devices in their own network (i.e., a Basic ServiceSet—BSS), but devices in other BSSs and indeed devices running otherprotocols before determining whether they can use the wireless medium.

What is therefore needed is a method for adapting a cellular wirelessprotocol to operate in an unlicensed channel in a manner that allows thecellular wireless protocol to share the unlicensed channel with otherdevices. Disclosed in some examples are systems, machine-readable media,methods, and cellular wireless devices which implement aListen-Before-Talk (LBT) access scheme for a device operating accordingto a cellular wireless protocol in an unlicensed band. A cellularwireless device may utilize the cellular wireless protocols in theunlicensed channels after the LBT access scheme has determined that thechannel (a defined range of frequencies in a particular spectrum) in theunlicensed spectrum is idle for a particular period of time.

A “cellular wireless device,” as used herein, is any device that isoperating according to a cellular wireless protocol. A “cellularwireless protocol” is a wireless protocol defining a cellular wirelessnetwork which is distributed over land areas called cells, each cellserved by at least one fixed-location transceiver, known as a cell siteor base station. These cell sites are interconnected to provide wirelessservices over a wide geographic area. Example cellular wirelessprotocols that may be adapted for transmission in the unlicensedchannels include cellular wireless protocols according to one of an LTEfamily of standards promulgated by the Third Generation PartnershipProject (3GPP), a Universal Mobile Telecommunications System (UMTS)family of standards promulgated by 3GPP, a Global System for MobileCommunications (GSM) family of standards, and the like. A cellularwireless device may be a base station such as a NodeB or an eNodeB, ormay be a mobile device such as a User Equipment (UE).

A cellular wireless device may use the licensed band for controllingtransmissions and other parameters used on the unlicensed band. This mayinclude obtaining CSI feedback, scheduling decisions on PDCCH, and thelike.

Example transmissions of the cellular wireless devices in the unlicensedchannel include transmissions to support one or more of Layer 1, Layer2, Layer 3, and other layers of these cellular protocols, for example,the Physical (PHY) layer, the Media Access Control (MAC) layer, theRadio Link Control (RLC) layer, the Packet Data Convergence Protocol(PDCP), and the Radio Resource Control (RRC) layers. Channelstransmitted in the unlicensed frequency may include any uplink datachannels, uplink control channels, downlink data channels, and downlinkcontrol channels. Examples include one or more of a Physical DownlinkShared Channel (PDSCH), a Physical Uplink Shared Channel (PUSCH), aPhysical Downlink Control Channel (PDCCH), and a Physical Uplink ControlChannel (PUCCH).

In some examples, a cellular wireless device such as a cellular basestation (e.g., eNodeB) may provide a cell with uplink and downlinkcapabilities in the licensed spectrum and also provide a supplementaldownlink (SDL) channel in an unlicensed spectrum. The SDL channel maycarry one or more LTE channels, such as a PDSCH. The LBT techniques maybe applied to the SDL channel to ensure that the unlicensed channels areidle and free of interference. In other examples, for uplink channels onthe unlicensed spectrum, the UE may be the cellular wireless devicewhich implements the LBT mechanisms. In some examples, the SDL may bescheduled on a PDCCH on the primary (licensed) frequencies. For example,the UE may be scheduled on the PDCCH of a licensed frequency forreceiving data on the SDL PDSCH on the unlicensed frequency (i.e., usingcross carrier scheduling). In some examples, the PDCCH that schedulesthe unlicensed channel may be sent on the unlicensed channel.

Aspects of the cellular wireless protocols may be modified in one ormore ways such as disclosed herein in order to operate within theunlicensed frequency spectrum. For example, an LBT access scheme may beimplemented in the cellular wireless protocol by the cellular wirelessdevice. In some examples, the cellular wireless device implementing anLBT access mode for the unlicensed band may listen to the channel for achannel listen time (a predetermined period of time). If the channel isidle for the channel listen time, the cellular wireless device may deemthat the channel is available for transmission.

In some examples, the cellular wireless device may determine that thechannel is idle by comparing the average detected power on the channelover the channel listen time to a predetermined power level threshold.If the average detected power is below the power level threshold, thenthe channel may be deemed available for transmission; otherwise, if theaverage detected power is above the power level threshold, then thechannel may be deemed busy.

Alternatively, instead of using an average detected power for theentirety of the channel listen time, if at any point during the channellisten time the detected channel power exceeds a power level threshold,then the cellular wireless device may deem the channel busy. Otherwise,if at no point during the channel listen time does the detected channelpower exceed the power level threshold, then the cellular wirelessdevice may deem the channel available.

Once the cellular wireless device has determined that the medium isavailable, in an asynchronous mode, the cellular wireless device maytransmit immediately. In other examples, in a synchronous mode, inresponse to determining that the wireless medium is available, thecellular wireless device may reserve the medium using a mediumreservation technique and wait for a sub-frame boundary of the cellularwireless protocol prior to transmitting.

Turning now to FIG. 1A, a timeline 1000 of a cellular wireless deviceoperating asynchronously in an unlicensed channel using an LBT mechanismis shown. The device measures the power level of the channel for thechannel listen time 1010. In FIG. 1A, the channel listen time 1010 isWμs. In some examples, the device determines that the medium is idle byconducting carrier sensing (CS) for the channel listen time 1010 andmeasuring the average power received over that period. If the averagepower received during the period is below a power level threshold (e.g.,−62 dBm), then the cellular wireless device may deem the medium to beidle and available for transmission. In some examples, this method ofdetecting that the medium is idle differs from that of Wi-Fi carriersensing. In Wi-Fi carrier sensing, A Wi-Fi device uses both an energydetection mechanism and a signal detection mechanism. If the Wi-Fidevice detects a Wi-Fi signal using the signal detection mechanism, theWi-Fi device assumes that the channel is occupied. In some examples, theLBT method disclosed herein uses only the energy detection mechanism andnot the Wi-Fi signal detection mechanisms.

Once the medium is idle, the cellular wireless device may optionallytransmit a reservation message (RSRV) 1020. This reservation message maybe any transmission which is designed to trigger the channel sensemechanism of one or more protocols operating on the channel of theunlicensed channel to view the channel as busy. One example reservationmessage 1020 may be a simple transmission above a certain power levelwhich is designed to trigger other wireless devices to detect thisenergy on the channel and to determine, based upon this energy, that thechannel is not idle.

In some examples, this message may be specific to a wireless protocoloperating in the unlicensed band. For example, a Wi-Fi message may betransmitted by the cellular wireless device on the unlicensed channel.The reservation message may reserve the channel for the transmissions ofthe cellular wireless device. In some examples, this message may be aWi-Fi Request-To-Send (RTS) or Clear-To-Send (CTS) message. Thesemessages may be sent by modifying the cellular wireless protocolcircuitry to transmit these messages of other protocols, or may be sentby adding protocol circuitry to send messages for other protocols (e.g.,adding a Wi-Fi chip to an eNodeB). The RTS or CTS messages may have aduration field which may specify the duration that the cellular wirelessdevice needs the unlicensed channel.

The RTS/CTS messages may be transmitted to one or more cellular wirelessdevices. The RTS/CTS message may be broadcast to the intended UEs. Theintended UEs may detect if the channel is idle. The RTS/CTS may betransmitted in time or frequency multiplexed manner.

The cellular wireless device may then transmit 1030 using the cellularprotocol. The cellular wireless device may send one or more uplink ordownlink cellular wireless channels carrying control or user data. Insome examples, the cellular wireless device may transmit one or morewireless sub-frames.

FIG. 1B shows one example method 1100 of employing an asynchronous LBTmechanism for a cellular wireless device according to some examples ofthe present disclosure. At operation 1110 the cellular wireless devicesenses the channel for a channel listen time (e.g., Wμs). At operation1120, the cellular wireless device determines if the channel is idle. Insome examples the cellular wireless device determines if the channel isidle by determining that an average received power for the channellisten time is below a power level threshold. If the channel is notdeemed to be idle, the device may go back and repeat operations 1110 and1120 until the channel is deemed idle. Once the channel is deemed idle,at operation 1130 the cellular wireless device may transmit data for theduration of the transmission opportunity (TXOP). In some examples, priorto transmitting data at operation 1130 the cellular wireless device maysend a reservation message. In some examples W may be 34 μs.

Turning now to FIG. 2A, a timeline 2000 of a cellular wireless deviceoperating synchronously in an unlicensed channel using an LBT mechanismis shown. The device senses that the medium is idle for a channel listentime 2010. In FIG. 2A, the channel listen time 2010 is Wμs. In someexamples, the device determines that the medium is idle by conductingcarrier sensing (CS) for the channel listen time and measuring theaverage power received. If the average power received during this periodis below a power level threshold, then the cellular wireless device maydeem the medium to be idle.

Once the medium is idle, the cellular wireless device may transmit areservation message (RSRV) 2020. In some examples, the reservationmessage 2020 may be a message from another wireless protocol, such as aWi-Fi message, and may be transmitted by the cellular wireless device.This message may reserve the wireless medium for the transmissions ofthe cellular wireless device. In some examples, this message may be aCTS or RTS message. These messages may be sent by modifying the cellularwireless protocol circuitry to transmit messages of other protocols, ormay be sent by adding protocol circuitry to send messages for otherprotocols (e.g., adding a Wi-Fi chip to an eNodeB).

In the case of FIG. 2A, the reservation message 2020 reserves thewireless medium for the cellular wireless device for the desiredtransmission opportunity (TXOP) 2040 as well as the amount of time tosend the data at the synchronized time (e.g., enough time to wait for asub-frame boundary). For example, the reservation message 2020 may bethe sum of the TXOP (transmission 2040) plus the idle period 2030 thatis the period of time that elapses before the start of the nextsub-frame of the cellular wireless protocol.

FIG. 2B shows an example method 2100 of employing a synchronous LBTmechanism for a cellular wireless device according to some examples ofthe present disclosure. At operation 2110 the cellular wireless devicesenses the channel for a channel listen time (e.g., Wμs). At operation2120, the cellular wireless device determines if the channel is idle. Insome examples the cellular wireless device determines that the channelis idle by determining that an average received power for the channellisten time is below a power level threshold. If the channel is notdeemed to be idle, the device may go back and repeat operations 2110 and2120 until the channel is deemed idle. Once the channel is deemed idle,at operation 2130 the cellular wireless device aligns to the sub-frameand transmits data for the duration of the transmission opportunity. Insome examples, prior to transmitting data at operation 2130 the cellularwireless device may send a reservation message.

In some examples, the LBT technique may include a backoff procedure toavoid collisions in the presence of a large number of transmitters. FIG.3 shows one example method of an LBT technique including a backoffprocedure. At operation 3010 the cellular wireless device senses thechannel for the channel listen time. If the average received power isnot below the power level threshold at operation 3020, the cellularwireless device may continue to sense the channel at operation 3010. Ifthe received power is below the power level threshold at operation 3020,and if the cellular wireless device determines not to implement thebackoff at operation 3030, the cellular wireless device may transmitdata for the duration of the transmission opportunity at operation 3040.As noted with respect to FIGS. 1&2, the cellular wireless device maysend a reservation message, and in some examples may align to asub-frame boundary.

If at operation 3030 the cellular wireless device determines that abackoff operation should be implemented, the cellular wireless devicemay calculate a random backoff contention window (CW) between anabsolute minimum (MIN) value and a current maximum value (CWT) atoperation 3050. The CWT may be initially set at the MIN level. Atoperation 3060 the cellular wireless device may decrement the contentionwindow CW. At operation 3070 it is determined if the CW is zero. If theCW is zero, the cellular wireless device may proceed to operation 3040to send data over the unlicensed channel. If the CW is not zero atoperation 3070 the cellular wireless device senses the channel for X μsat operation 3080. In some examples X is 9 μs. X and W may be the sameor different values. In some examples, MIN may be 3 and MAX may be 1023.

If the received power is below a predetermined threshold at operation3090, then the cellular wireless device decrements CW at operation 3060and the cellular wireless device repeats operations 3070, 3080, and 3090until the CW is zero (at which time the cellular wireless devicetransmits on the unlicensed channel at operation 3040) or until thereceived power is not below the threshold at operation 3090. If thereceived power is not below the threshold at operation 3090, then atoperation 3095 the cellular wireless device goes back to operation 3010.In some examples the threshold power level at operation 3090 may be thesame as or different than the threshold power level at operation 3020.In some examples, the thresholds may be −62 dbm. The backoff process maybe deemed successful once the CW is zero.

Once data is transmitted at operation 3040, in some examples, thecellular wireless device may determine if a collision occurred duringthe transmission. In some examples, to do this, the cellular wirelessdevice may calculate a transport block error (TBE) rate at operation3100. At operation 3110 the TBE may be compared to a predetermined errorthreshold. In some examples the predetermined error threshold may be0.5. If the TBE is below the predetermined error threshold, the cellularwireless device may infer that the transmission was successful and wasnot interfered with. In this case, at operation 3120, the currentmaximum value CWT may be set to the MIN value, which may be used thenext time the CW is determined. At this point, the flow ends until thenext time the cellular wireless device has data to send and starts theprocess over at operation 3010. If the TBE is above or equal to thepredetermined threshold, then the cellular wireless device may set thecurrent maximum CWT to be double the previous CWT up to a global maximumvalue MAX at operation 3130. A new backoff CW is selected at operation3050 and the backoff process is repeated as the cellular wireless devicewill attempt to retransmit the blocks that had errors.

In contrast to Wi-Fi, the LBT mechanism disclosed herein, in someexamples, utilizes a transport block error measurement. TBE is definedspecifically by the cellular wireless protocol, but in general is ameasure of how successful a data transmission is over the air at thePhysical/MAC layer level. For LTE, if a transport block is successfullydecoded then the transmission is successful. Successful decoding is whenthe Cyclic Redundancy Check (CRC) calculated by the receiver matches theCRC sent in the transport block. The TBE is a percentage or ratio ofsuccessful blocks. Wi-Fi, in contrast, assumes that a failure to receivean acknowledgement of a packet indicates a collision.

As already noted, in some examples, at operation 3040 the cellularwireless device may send a reservation message in order to prevent otherwireless devices from accessing the medium. Also, at operation 3040 thecellular wireless device may wait for a cellular sub-frame boundarybefore transmitting.

Turning now to FIG. 4, a schematic of a cellular wireless device 4000 isshown according to some examples. The cellular wireless device 4000 maybe any device that is capable of communicating using a licensed cellularprotocol. The cellular wireless device 4000 may be a nodeB, an eNodeB, aUE, a Base Transceiver Station (BTS), a Wi-Fi access point, a cellphone, a smart phone, a desktop computer, a laptop computer, a medicaldevice (e.g., a heart rate monitor, a blood pressure monitor, or thelike), a wearable device (e.g., computing glasses, a smart watch), orthe like.

The cellular wireless device 4000 may contain a first wirelesstransceiver 4030, a second wireless transceiver 4040, and controlcircuitry 4020 for controlling the first and second wirelesstransceivers. The first wireless transceiver 4030 may operate on anunlicensed channel and in some examples, implement a wireless protocolthat is not a cellular wireless protocol. In some examples, the firstwireless transceiver 4030 may implement a wireless protocol thatoperates in the unlicensed channels, such as an IEEE 802.11 wirelessprotocol, a Bluetooth wireless protocol, a Bluetooth Low Energy (BLE)wireless protocol, a Zigbee wireless protocol, or the like. In someexamples, the first wireless transceiver 4030 may determine whether theunlicensed channel is occupied with other traffic. In some examples, thefirst transceiver 4030 may detect the power level on the unlicensedchannel and if the average power level is below a particular thresholdfor a predetermined period of time, then the control circuitry 4020 maydetermine that the channel is unoccupied. If the average power level isabove the particular threshold for the predetermined period of time,then the control circuitry 4020 may determine that the channel isoccupied. If the channel is occupied, control circuitry 4020 mayinstruct the first transceiver 4030 to continue to sense the channeluntil the received average power level is below the predeterminedthreshold for the predetermined period of time.

Control circuitry 4020 may control the backoff process once the channelis deemed unoccupied. The control circuitry 4020 may, in cooperationwith the first transceiver 4030, cause the operations of FIG. 3 to beimplemented, such as selecting a random contention window, decrementingthe contention window, using the first transceiver 4030 to sense thechannel for X μs, determining if the backoff period is over, or, ifactivity is detected on the channel during the backoff period, signalingthe first transceiver 4030 to once again determine if the medium is freeby detecting the power level on the unlicensed channel for a channellisten period of time. Once the control circuitry and first transceiverhave determined that the channel is once again free, the controlcircuitry 4020 will start over and once again implement the backoffprocedure

The second wireless transceiver 4040 may implement a cellular wirelessprotocol and may generally transmit over a licensed frequency. Examplecellular wireless protocols may include a Long Term Evolution (LTEfamily of standards promulgated by the Third Generation PartnershipProject (3GPP), Universal Mobile Telecommunications (UMTS) promulgatedby 3GPP, an Institute for Electrical and Electronics Engineers (IEEE)802.16 standard known as Worldwide Interoperability for Microwave Access(WiMAX), and the like. The second transceiver 4040 may provide for oneor more protocol layers of the cellular wireless protocol to enablecommunications. For example, if the cellular wireless device 4000 is aneNodeB, the second transceiver 4040 provides the functionality toimplement the eNodeB. If the cellular wireless device 4000 is a UE, thesecond transceiver 4040 provides the functionality to connect to thecellular network and transfer data across that network. The secondtransceiver 4040 may utilize the licensed bandwidth, but may also havecircuitry to send and receive data across the unlicensed bandwidth.

Control circuitry 4020 may control the first transceiver 4030, as wellas second transceiver 4040. When the control circuitry 4020 determinesthat the unlicensed channels should be used for the cellular wirelessprotocol, the control circuitry 4020 may determine when the channel isfree using first transceiver 4030, and in some examples, to reserve thechannel using a channel reservation message via first transceiver 4030.Once the channel is free, the control circuitry 4020 may instruct eitherthe first or second transceivers 4030 and 4040 to transmit on theunlicensed band.

In some examples, the cellular wireless device 4000 may send areservation message on the unlicensed channels. In some examples, thereservation message has a duration field which may be set to theduration of cellular data transfer (e.g., a sub-frame). In someexamples, the cellular wireless device 4000 may not begin transmittinguntil a sub-frame boundary. In these examples, if a reservation messageis sent, the reservation message may have a duration equal to theduration of cellular data transfer plus the amount of time until thenext sub-frame boundary.

After the transmission, the control circuitry 4020 may determine if thetransmission was successful. In some examples, the transmission may bedeemed successful if a TBE measurement is below a predeterminedthreshold. If the TBE measurement is below the predetermined threshold,the contention window for the next transmission may be set to theminimum contention window value (MIN) by setting the maximum value usedin the random selection (e.g., at operation 3050 in FIG. 3) to theminimum value (MIN).

If the TBE measurement is not below the predetermined threshold, thenext contention window may be doubled and the backoff process may bestarted for retransmitting the data.

FIG. 5 illustrates a block diagram of an example machine 5000 upon whichany one or more of the techniques (e.g., methodologies) discussed hereinmay be performed. In alternative embodiments, the machine 5000 mayoperate as a standalone device or may be connected (e.g., networked) toother machines. In a networked deployment, the machine 5000 may operatein the capacity of a server machine, a client machine, or both inserver-client network environments. In an example, the machine 5000 mayact as a peer machine in peer-to-peer (P2P) (or other distributed)network environment. The machine 5000 may be a cellular wireless device,a wireless device, or the like. Example cellular wireless devicesinclude an eNodeB, a UE, a personal computer (PC), a tablet PC, aset-top box (STB), a personal digital assistant (PDA), a mobiletelephone, a web appliance, a network router, switch, or bridge, or anymachine capable of executing instructions (sequential or otherwise) thatspecify actions to be taken by that machine. Further, while only asingle machine is illustrated, the term “machine” shall also be taken toinclude any collection of machines that individually or jointly executea set (or multiple sets) of instructions to perform any one or more ofthe methodologies discussed herein, such as cloud computing, software asa service (SaaS), or other computer cluster configurations.

Examples, as described herein, may include, or may operate on, logic ora number of components, modules, circuitry, or mechanisms. Modules andcircuitry are tangible entities (e.g., hardware) capable of performingspecified operations and may be configured or arranged in a certainmanner. In an example, circuits may be arranged (e.g., internally orwith respect to external entities such as other circuits) in a specifiedmanner as circuitry. In an example, the whole or part of one or morecomputer systems (e.g., a standalone, client, or server computer system)or one or more hardware processors may be configured by firmware orsoftware (e.g., instructions, an application portion, or an application)as circuitry that operates to perform specified operations.

Accordingly, the term “circuitry” is understood to encompass a tangibleentity, be that an entity that is physically constructed, specificallyconfigured (e.g., hardwired), or temporarily (e.g., transitorily)configured (e.g., programmed) to operate in a specified manner or toperform part or all of any operation described herein. Consideringexamples in which circuitry is temporarily configured, each of thecircuits need not be instantiated at any one moment in time. Forexample, where the circuits comprise a general-purpose hardwareprocessor configured using software, the general-purpose hardwareprocessor may be configured as respective different circuitry atdifferent times. Software may accordingly configure a hardwareprocessor, for example, to constitute a particular circuit at oneinstance of time and to constitute a different circuit at a differentinstance of time.

The machine (e.g., computer system) 5000 may include a hardwareprocessor 5002 (e.g., a central processing unit (CPU), a graphicsprocessing unit (GPU), a hardware processor core, or any combinationthereof), a main memory 5001, and a static memory 5006, some or all ofwhich may communicate with each other via an interlink (e.g., bus) 5008.The machine 5000 may further include a display unit 5010, analphanumeric input device 5012 (e.g., a keyboard), and a user interface(UI) navigation device 5014 (e.g., a mouse). In an example, the displayunit 5010, alphanumeric input device 5012, and UI navigation device 5014may be a touch screen display. The machine 5000 may additionally includea storage device (e.g., drive unit) 5016, a signal generation device5018 (e.g., a speaker), a network interface device 5020, and one or moresensors 5021, such as a global positioning system (GPS) sensor, compass,accelerometer, or other sensor. The machine 5000 may include an outputcontroller 5028, such as a serial (e.g., universal serial bus (USB)),parallel, or other wired or wireless (e.g., infrared (IR), near fieldcommunication (NFC), etc.) connection to communicate with or control oneor more peripheral devices (e.g., a printer, card reader, etc.).

The storage device 5016 may include a machine readable medium 5022 onwhich is stored one or more sets of data structures or instructions 5024(e.g., software) embodying or utilized by any one or more of thetechniques or functions described herein. The instructions 5024 may alsoreside, completely or at least partially, within the main memory 5001,within the static memory 5006, or within the hardware processor 5002during execution thereof by the machine 5000. In an example, one or anycombination of the hardware processor 5002, the main memory 5001, thestatic memory 5006, or the storage device 5016 may constitute machinereadable media.

While the machine readable medium 5022 is illustrated as a singlemedium, the term “machine readable medium” may include a single mediumor multiple media (e.g., a centralized or distributed database, and/orassociated caches and servers) configured to store the one or moreinstructions 5024.

The term “machine readable medium” may include any medium that iscapable of storing, encoding, or carrying instructions for execution bythe machine 5000 and that cause the machine 5000 to perform any one ormore of the techniques of the present disclosure, or that is capable ofstoring, encoding, or carrying data structures used by or associatedwith such instructions. A machine readable medium may include anon-transitory machine readable medium. A machine-readable medium is nota transitory propagating signal. Non-limiting machine readable mediumexamples may include solid-state memories, and optical and magneticmedia. Specific examples of machine readable media may includenon-volatile memory, such as semiconductor memory devices (e.g.,Electrically Programmable Read-Only Memory (EPROM), ElectricallyErasable Programmable Read-Only Memory (EEPROM)) and flash memorydevices; magnetic disks, such as internal hard disks and removabledisks; magneto-optical disks; Random Access Memory (RAM); and CD-ROM andDVD-ROM disks.

The instructions 5024 may further be transmitted or received over acommunications network 5026 using a transmission medium via the networkinterface device 5020 utilizing any one of a number of transferprotocols (e.g., frame relay, internet protocol (IP), transmissioncontrol protocol (TCP), user datagram protocol (UDP), hypertext transferprotocol (HTTP), etc.). Example communication networks may include alocal area network (LAN), a wide area network (WAN), a packet datanetwork (e.g., the Internet), mobile telephone networks (e.g., cellularnetworks), Plain Old Telephone (POTS) networks, and wireless datanetworks (e.g., IEEE 802.11 family of standards known as Wi-Fi®, IEEE802.16 family of standards known as WiMax®), IEEE 802.15.4 family ofstandards, and peer-to-peer (P2P) networks, among others. In an example,the network interface device 5020 may include one or more physical jacks(e.g., Ethernet, coaxial, or phone jacks) or one or more antennas toconnect to the communications network 5026. In an example, the networkinterface device 5020 may include a plurality of antennas to wirelesslycommunicate using at least one of single-input multiple-output (SIMO),multiple-input multiple-output (MIMO), or multiple-input single-output(MISO) techniques. The term “transmission medium” shall be taken toinclude any intangible medium that is capable of storing, encoding, orcarrying instructions for execution by the machine 5000, and includesdigital or analog communications signals or other intangible media tofacilitate communication of such software.

OTHER NOTES AND NON-LIMITING EXAMPLES

Example 1 includes subject matter (such as a device, apparatus, ormachine) comprising: a first transceiver to transmit and receive in anunlicensed channel using a first wireless protocol; a second transceiverto transmit and receive in a licensed channel in accordance with acellular wireless protocol; a controller to: determine, via the firsttransceiver, that an average energy of the unlicensed channel over apredetermined period of time is below a predetermined threshold, and inresponse: send a wireless reservation message on the unlicensed channelvia the first transceiver to reserve the unlicensed channel for atransmission of a Supplemental Downlink (SDL) Physical Downlink SharedChannel (PDSCH); schedule at least one User Equipment (UE) serviced bythe eNodeB to receive data on the SDL PDSCH in the unlicensed channelvia a Physical Downlink Control Channel (PDCCH) on the licensed channeltransmitted by the second transceiver; and transmit the SDL PDSCH overthe unlicensed channel at a cellular sub-frame boundary via the firsttransceiver.

In Example 2, the subject matter of Example 1 may include, wherein thecellular wireless protocol is a Long Term Evolution (LTE) or Long TermEvolution-Advanced (LTE-A) family of Standards defined by the ThirdGeneration Partnership (3GPP).

In Example 3, the subject matter of any one of Examples 1 to 2 mayinclude, wherein the first wireless protocol is a protocol according toan Institute for Electrical and Electronics Engineers (IEEE) 802.11protocol.

In Example 4, the subject matter of any one of Examples 1 to 3 mayinclude, wherein the wireless reservation message is one of: a Clear toSend (CTS) message or a Request to Send (RTS) message.

In Example 5, the subject matter of any one of Examples 1 to 4 mayinclude, wherein the controller is to implement a backoff process, andwherein the controller is to refrain from sending the reservationmessage, scheduling the UE and transmitting the SDL PDSCH until thebackoff process is successful.

In Example 6, the subject matter of any one of Examples 1 to 5 mayinclude, wherein, a backoff length is determined based on a previoustransmission.

In Example 7, the subject matter of any one of Examples 1 to 6 mayinclude, wherein the unlicensed channel is a channel in the Industrial,Scientific, and Medical (ISM) bands.

In Example 8, the subject matter of any one of Examples 1 to 7 mayinclude, wherein the cellular sub-frame boundary is a start of an LTE orLTE-A sub-frame.

In Example 9, the subject matter of any one of Examples 1 to 8 mayinclude, wherein the wireless reservation message includes a durationfield that is set to a time that is at least the sum of a time needed toreach the beginning of the sub-frame boundary and the time needed totransmit the SDL PDSCH.

In Example 10, the subject matter of any one of Examples 1 to 9 mayinclude, wherein the second transceiver is configured to provide a PDCCHin a licensed channel.

Example 11 includes subject matter (such as a device, apparatus, ormachine) comprising: sense a first channel for a predetermined period oftime, the first channel a wireless channel that is not exclusivelylicensed for cellular wireless communications; determine that an averagereceived power of the first channel indicates that the first channel isidle during the predetermined period of time; and in response to thedetermination that the first channel is idle: schedule at least one UserEquipment (UE) serviced by the eNodeB to receive data on a PhysicalDownlink Shared Channel (PDSCH) transmitted on the first channel;communicate the schedule to the UE via a control channel on a secondchannel, the second channel a wireless channel that is licensed forcellular wireless communications; and transmit the PDSCH over the firstchannel via the first transceiver.

In Example 12, the subject matter of Example 11 may include, wherein theinstructions configure the eNodeB to at least send a reservation messageon the first channel in response to the determination that the firstchannel is idle.

In Example 13, the subject matter of any one of Examples 11 to 12 mayinclude, wherein the reservation message is a message defined accordingto one of an Institute of Electrical and Electronics Engineers (IEEE)802.11 family of standards.

In Example 14, the subject matter of any one of Examples 11 to 13 mayinclude, wherein the reservation message has a duration field that is atleast as large as a sum of a time until the sub-frame boundary and atime needed to send the sub-frame.

In Example 15, the subject matter of any one of Examples 11 to 14 mayinclude, wherein the operations to transmit the PDSCH include operationsto wait to transmit until a sub-frame boundary of the eNodeB.

In Example 16, the subject matter of any one of Examples 11 to 15 mayinclude, wherein the instructions further configure the eNodeB toimplement a backoff procedure prior to scheduling the UE.

In Example 17, the subject matter of any one of Examples 11 to 16 mayinclude, wherein the eNodeB operates according to one of a Long TermEvolution (LTE) or Long Term Evolution-Advanced (LTE-A) wirelessprotocol.

Example 18 includes subject matter (such as a method, means forperforming acts, machine readable medium including instructions thatwhen performed by a machine cause the machine to performs acts, or anapparatus to perform) comprising: at an eNodeB: determine, via a firsttransceiver, that an average energy of a first channel over apredetermined period of time is below a predetermined threshold, thefirst channel a wireless channel that is not exclusively licensed forcellular wireless, and in response: select a random backoff period;determine that the average energy of the first channel over the backoffperiod is below a second threshold; schedule at least one User Equipment(UE) serviced by the eNodeB to receive data on a Supplemental Downlink(SDL) Physical Downlink Shared Channel (PDSCH) on the first channel;communicate the schedule to the UE by transmission of a PhysicalDownlink Control Channel (PDCCH) on a second channel by a secondtransceiver, the second channel a wireless channel that is licensed forcellular wireless; and transmit the SDL PDSCH over the unlicensedchannel at a cellular sub-frame boundary via the first transceiver.

In Example 19, the subject matter of Example 18 may include providing aPDSCH on the second channel.

In Example 20, the subject matter of any one of Examples 18 to 19 mayinclude, wherein the unlicensed channel is a frequency between 2.4 Ghzand 2.5 Ghz.

In Example 21, the subject matter of any one of Examples 18 to 20 mayinclude, sending a wireless reservation message on the first channel.

In Example 22, the subject matter of any one of Examples 18 to 21 mayinclude, wherein the wireless reservation message is a broadcastmessage.

In Example 23, the subject matter of any one of Examples 18 to 22 mayinclude, wherein the wireless reservation message is a Clear To Send(CTS) message.

In Example 24, the subject matter of any one of Examples 18 to 23 mayinclude, wherein the CTS message is transmitted in time multiplexed orfrequency multiplexed manner.

In Example 25, the subject matter of any one of Examples 18 to 24 mayinclude, wherein the wireless reservation message has a duration fieldthat is set to a value that is at least the time until the sub-frameboundary plus the time necessary to transmit a PDSCH sub-frame.

In Example 26, the subject matter of any one of Examples 18 to 25 mayinclude, wherein the predetermined threshold and the second thresholdare the same value.

In Example 27, the subject matter of any one of Examples 18 to 26 mayinclude, wherein the predetermined threshold and the second thresholdare different values.

Example 28 includes subject matter (such as a device, apparatus, ormachine) comprising: means for determine, via a first transceiver, thatan average energy of a first channel over a predetermined period of timeis below a predetermined threshold, the first channel a wireless channelthat is not exclusively licensed for cellular wireless, and in response:means for selecting a random backoff period; means for determining thatthe average energy of the first channel over the backoff period is belowa second threshold; means for scheduling at least one User Equipment(UE) serviced by the eNodeB to receive data on a Supplemental Downlink(SDL) Physical Downlink Shared Channel (PDSCH) on the first channel;means for communicating the schedule to the UE by transmission of aPhysical Downlink Control Channel (PDCCH) on a second channel by asecond transceiver, the second channel a wireless channel that islicensed for cellular wireless; and means for transmitting the SDL PDSCHover the unlicensed channel at a cellular sub-frame boundary via thefirst transceiver.

In Example 29, the subject matter of Example 28 may include, means forproviding a PDSCH on the second channel.

In Example 30, the subject matter of any one of Examples 28 to 29 mayinclude, wherein the unlicensed channel is a frequency between 2.4 Ghzand 2.5 Ghz.

In Example 31, the subject matter of any one of Examples 28 to 30 mayinclude, means for sending a wireless reservation message on the firstchannel.

In Example 32, the subject matter of any one of Examples 28 to 31 mayinclude, wherein the wireless reservation message is a broadcastmessage.

In Example 33, the subject matter of any one of Examples 28 to 32 mayinclude, wherein the wireless reservation message is a Clear To Send(CTS) message.

In Example 34, the subject matter of any one of Examples 28 to 33 mayinclude, wherein the wireless reservation message has a duration fieldthat is set to a value that is at least the time until the sub-frameboundary plus the time necessary to transmit a PDSCH sub-frame.

In Example 35, the subject matter of any one of Examples 28 to 34 mayinclude, wherein the predetermined threshold and the second thresholdare the same value.

In Example 36, the subject matter of any one of Examples 28 to 35 mayinclude, wherein the predetermined threshold and the second thresholdare different values.

Example 37 includes subject matter (such as a device, apparatus, ormachine) comprising: one or more processors configured to: sense a firstchannel for a predetermined period of time, the first channel a wirelesschannel that is not exclusively licensed for cellular wirelesscommunications; determine that an average received power of the firstchannel indicates that the first channel is idle during thepredetermined period of time; and in response to the determination thatthe first channel is idle: schedule at least one User Equipment (UE)serviced by the eNodeB to receive data on a Physical Downlink SharedChannel (PDSCH) transmitted on the first channel; communicate theschedule to the UE via a control channel on a second channel, the secondchannel a wireless channel that is licensed for cellular wirelesscommunications; and transmit the PDSCH over the first channel via thefirst transceiver.

In Example 38, the subject matter of Example 37 may include, wherein theone or more processors are configured to send a reservation message onthe first channel in response to the determination that the firstchannel is idle.

In Example 39, the subject matter of any one of Examples 37 to 38 mayinclude wherein the reservation message is a message defined accordingto one of an Institute of Electrical and Electronics Engineers (IEEE)802.11 family of standards.

In Example 40, the subject matter of any one of Examples 37 to 39 mayinclude, wherein the reservation message has a duration field that is atleast as large as a sum of a time until the sub-frame boundary and atime needed to send the sub-frame.

In Example 41, the subject matter of any one of Examples 37 to 40 mayinclude wherein the one or more processors are configured to transmitthe PDSCH include operations to wait to transmit until a sub-frameboundary.

In Example 42, the subject matter of any one of Examples 37 to 41 mayinclude wherein the one or more processors are configured to implement abackoff procedure prior to scheduling the UE.

In Example 43, the subject matter of any one of Examples 37 to 42 mayinclude wherein the cellular wireless device operates according to oneof a Long Term Evolution (LTE) or Long Term Evolution-Advanced (LTE-A)wireless protocol.

What is claimed is:
 1. An eNodeB comprising: a first transceiver totransmit and receive in an unlicensed channel using a first wirelessprotocol; a second transceiver to transmit and receive in a licensedchannel in accordance with a cellular wireless protocol; a controllerto: determine, via the first transceiver, that an average energy of theunlicensed channel over a predetermined period of time is below apredetermined threshold, and in response: send a wireless reservationmessage on the unlicensed channel via the first transceiver to reservethe unlicensed channel for a transmission of a Supplemental Downlink(SDL) Physical Downlink Shared Channel (PDSCH); schedule at least oneUser Equipment (UE) serviced by the eNodeB to receive data on the SDLPDSCH in the unlicensed channel via a Physical Downlink Control Channel(PDCCH) on the licensed channel transmitted by the second transceiver;and transmit the SDL PDSCH over the unlicensed channel at a cellularsub-frame boundary via the first transceiver.
 2. The eNodeB of claim 1,wherein the cellular wireless protocol is a Long Term Evolution (LTE) orLong Term Evolution-Advanced (LTE-A) family of Standards defined by theThird Generation Partnership (3GPP).
 3. The eNodeB of claim 2, whereinthe first wireless protocol is a protocol according to an Institute forElectrical and Electronics Engineers (IEEE) 802.11 protocol.
 4. TheeNodeB of claim 1, wherein the wireless reservation message is one of: aClear to Send (CTS) message or a Request to Send (RTS) message.
 5. TheeNodeB of claim 1, wherein the controller is to implement a backoffprocess, and wherein the controller is to refrain from sending thereservation message, scheduling the UE and transmitting the SDL PDSCHuntil the backoff process is successful.
 6. The eNodeB of claim 5,wherein the unlicensed channel is a channel in the Industrial,Scientific, and Medical (ISM) bands.
 7. The eNodeB of claim 1, whereinthe cellular sub-frame boundary is a start of an LTE or LTE-A sub-frame.8. The eNodeB of claim 1, wherein the wireless reservation messageincludes a duration field that is set to a time that is at least the sumof a time needed to reach the beginning of the sub-frame boundary andthe time needed to transmit the SDL PDSCH.
 9. The eNodeB of claim 1,wherein the second transceiver is configured to provide a PDCCH in alicensed channel.
 10. A non-transitory machine-readable medium thatstores instructions, for execution by one or more processors of aneNodeB, which configure the eNodeB to perform operations to at least:sense a first channel for a predetermined period of time, the firstchannel a wireless channel that is not exclusively licensed for cellularwireless communications; determine that an average received power of thefirst channel indicates that the first channel is idle during thepredetermined period of time; and in response to the determination thatthe first channel is idle: schedule at least one User Equipment (UE)serviced by the eNodeB to receive data on a Physical Downlink SharedChannel (PDSCH) transmitted on the first channel; communicate theschedule to the UE via a control channel on a second channel, the secondchannel a wireless channel that is licensed for cellular wirelesscommunications; and transmit the PDSCH over the first channel via thefirst transceiver.
 11. The non-transitory machine-readable medium ofclaim 10, wherein the instructions configure the eNodeB to at least senda reservation message on the first channel in response to thedetermination that the first channel is idle.
 12. The non-transitorymachine-readable medium of claim 11, wherein the reservation message isa message defined according to one of an Institute of Electrical andElectronics Engineers (IEEE) 802.11 family of standards.
 13. Thenon-transitory machine-readable medium of claim 12, wherein thereservation message has a duration field that is at least as large as asum of a time until the sub-frame boundary and a time needed to send thesub-frame.
 14. The non-transitory machine-readable medium of claim 10,wherein the operations to transmit the PDSCH include operations to waitto transmit until a sub-frame boundary of the eNodeB.
 15. Thenon-transitory machine-readable medium of claim 10, wherein theinstructions further configure the eNodeB to implement a backoffprocedure prior to scheduling the UE.
 16. The non-transitorymachine-readable medium of claim 10, wherein the eNodeB operatesaccording to one of a Long Term Evolution (LTE) or Long TermEvolution-Advanced (LTE-A) wireless protocol.
 17. A method comprising:at an eNodeB: determine, via a first transceiver, that an average energyof a first channel over a predetermined period of time is below apredetermined threshold, the first channel a wireless channel that isnot exclusively licensed for cellular wireless, and in response: selecta random backoff period; determine that the average energy of the firstchannel over the backoff period is below a second threshold; schedule atleast one User Equipment (UE) serviced by the eNodeB to receive data ona Supplemental Downlink (SDL) Physical Downlink Shared Channel (PDSCH)on the first channel; communicate the schedule to the UE by transmissionof a Physical Downlink Control Channel (PDCCH) on a second channel by asecond transceiver, the second channel a wireless channel that islicensed for cellular wireless; and transmit the SDL PDSCH over theunlicensed channel at a cellular sub-frame boundary via the firsttransceiver.
 18. The method of claim 17 comprising providing a PDSCH onthe second channel.
 19. The method of claim 17, wherein the unlicensedchannel is a frequency between 2.4 Ghz and 2.5 Ghz.
 20. The method ofclaim 17, comprising sending a wireless reservation message on the firstchannel.
 21. The method of claim 20, wherein the wireless reservationmessage is a broadcast message.
 22. The method of claim 21, wherein thewireless reservation message is a Clear To Send (CTS) message.
 23. Themethod of claim 21, wherein the wireless reservation message has aduration field that is set to a value that is at least the time untilthe sub-frame boundary plus the time necessary to transmit a PDSCHsub-frame.
 24. The method of claim 21, wherein the predeterminedthreshold and the second threshold are the same value.
 25. The method ofclaim 21, wherein the predetermined threshold and the second thresholdare different values.